1. Field of the Invention
The present invention generally relates to a process for the preparation of trifluoromethyl iodide. More particularly, the present invention relates to a process for the preparation of trifluoromethyl iodide from CF3—W and IFn, wherein W is H, Br, Cl, COOH, COCl, COOCH3, COOC2H5, COCH3, COPh, CF3, Si(CH3)3, SPh, SCH3, SSCF3, SSPh, SSCH3, or SO2Cl, and n is 1, 3, 5 or 7, wherein in process is carried out in the presence or absence of oxygen co-feed.
2. Description of the Prior Art
An article by Dhooge et al. in the Proceedings of the 4th Conference on Aerospace Materials, Processes, and Environmental Technology, pages 259–268 (2000), describes vapor phase production process for the preparation of CF3I by the reaction between CHF3 with I2 in the presence of a catalyst including alkali metal salts supported on an activated carbon carrier. The mechanism of the reaction appears to proceeds via :CF2 (difluoro carbene) intermediates that are formed on the catalyst surface, followed by carbene disproportionation to •CF3 radicals, followed by reaction with 12 to give CF3I (see Nagasaki, Noritaka et al., Catalysis Today (2004), 88(3–4), 121–126).
JP 52068110 (1977) describes the preparation of CF3I by vapor-phase reaction of Freon 23 with iodine in the presence of alkali or alkaline earth metal salts.
DE 1805457 (1970) describes the preparation of CF3I and C2F5I from the reaction of corresponding bromides and KI without solvent.
Naumann et al., J. Fluorine Chem., 67(1), 91–3 (1994) describes the preparation of CF3I from CF3Br by a multi-step reaction, which employs elemental Zn.
European Patent Application EP 266,281 A1 (1988) describes the preparation of CF3I from CF3Br by contact with a metal or an alkali metal dithionite and SO2 followed by treatment with iodine in a carboxylic or sulfonic acid.
Lee, K.-H. et al., Hwahak Konghak, 39(2), 144–149 (2001) describes the preparation of CF3I by iodination of CF3CO2H with iodine using a flow reactor over various salt-impregnated catalysts.
Su, D. et al., J. Chem. Soc., Chem. Commun., (11), 807–8 (1992) describes the preparation of CF3I by treatment of XCF2CO2Me (X=Cl or Br) with iodine in the presence of potassium fluoride and copper (I) iodide.
Chiriac, M. et al., Inst. Tehnol. Izot. Mol., 33(11), 1018–20 (1982) describes the preparation of CF3I from AgO2CCF3 (silver trifluoroacetate).
However, in view of the high cost of the raw materials required and the formation of undesirable solid by-products that are difficult to dispose of, and because of the adverse impact of the solid by-products on the environment, none of the above described methods provide a practical and economical process that can be adapted to large scale production of high purity CF3I. In addition, there are no reports in the literature of any catalytic vapor-phase process for making CF3I in high yield. Accordingly, the discovery of a high yield, catalytic vapor-phase process, which avoids the formation of solid by-products and the adverse impact of such solid by-products on the environment would be welcome by the Chemical Industry.
These problems can be avoided by the use of a process for the preparation of trifluoromethyl iodide from CF3—W and IFn wherein W is H, Br, Cl, COOH, COCl, COOCH3, COOC2H5, COCH3, COPh, CF3, Si(CH3)3, SPh, SCH3, SSCF3, SSPh, SSCH3, or SO2Cl, and n is 1, 3, 5, or 7.
The present invention provides such a high yield, catalytic vapor-phase process, which avoids the formation of solid by-products and the adverse impact of such solid by-products on the environment.